Blade pin retention



Jan. 10, 1967 E, w SPEARS, JR 3,297,302

BLADE PIN RETENTION Filed Oct. 24, 1965 l /7 guillaumm @Willi/105m? United States Patent O 3,297,302 BLADE PIN RETENTION Esten W. Spears, Jr., Indianapolis, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 24, 1965, Ser. No. 504,945 7 Claims. (Cl. 253-77) My invention relates generally to the mounting of blades in a rotor and more specifically to a blade pin retainer for a pin-connected type of rotor fblade mounting. Today nearly all of the bladed rotors used in turbomachinery comprise a rotor or wheel in which the blades are individually mounted on the :periphery of the wheel. One of the general types of construction is that in which the blades have apertures in their roots which align with apertures in the rotor periphery so as to receive a pin which hinges the blades to the rotor. My invention is specifically directed toward means for retaining this pin in the aligned apertures. Such a retention means should incorporate the following desirable features. The retention means should be capable of two-way retention since the pin if unheaded is capable of withdrawal from either direction. It is also desirable that each of the pins be individually retained so that a single blade may be changed without disturbing the remainder of the blades. It is also desirable that no mounting apertures or other weakening types of modification be required for the rotor and that the retaining means be of relatively cheap manufacture and structural simplicity,

The object `of my invention then is to provide a blade pin retainer which incorporates all of the above features.

Bladed rotors, like all rotating machinery, usually require static and dynamic balancing. Another object of my invention is to include means on the blade pin retainers for balancing the rotor. This feature integrates two functions into a single device, that is, blade retention and rotor balancing.

Other objects and advantages of this invention will be understood by reference to the following detailed description and the accompanying drawings -Whereinz FIGURE l is an elevation view partially in cross section of a pin-connected bladed rotor provided with a blade pin retainer in accordance with my invention.

FIGURE 2 is a section taken substantially along the line 2 2 of FIGURE l and looking in the direction of the arrows.

FIGURE 3 is a section taken substantially along the line 3 3 of FIGURE 1 and looking in the direction of the arrows.

FIGURE 4 is a section taken substantially along the line 4 4 of FIGURE l and looking in the direction of the arrows.

Referring to FIGURE l in detail, I have shown a portion of a rotor 12 having an enlarged rim 13. The rim 13 has a pair of spaced circumferential grooves 14 to define three `lands 15. As shown, the middle land 15 is bifurcated by a narrow groove but this is not necessary to the invention. The spaced grooves 14 are adapted to receive a pair of depending tangs 16 on a blade root 17. The tangs 16 have aligned apertures 20 which are aligned with one set of a number of circumferentially spaced sets of aligned apertures 22 in the rotor 12 so as to receive a pin 24 to radially mount the blade 18 to the `rotor 12. The left land 15 has a flange 25 extending axially from the outer face of its periphery. The axial ange 25 has an inwardly opening groove 26 which is axially aligned with a circumferential groove 30 adjacent the left end of the pin 24. A blade pin retainer indicated generally at 32 has marginal portions disposed in each of the grooves 26 and 30 and provides two-way retention of the pin 24 within the aligned apertures 20 and '22. Each of the ice blade pin retainers 32 comprises a lock tab 34 and a retainer element 36.

Referring now to FIGURE 2, the lock tab 34 is shown in greater detail. The lock tab 34 is a at piece of soft metal having an insertable arcuate lportion 38 at its right side. The maximum width or thickness `of the arcuate insertable portion is no greater than the radial distance between the Ebottom axial wall of the groove 26 and the bottom axial wall of-the pin groove 30. The Aright hand end portion 42 of the insertable lock tab portion 38 is bendable. The left hand portion 40 of the lock tab 34 is enlarged and curves around and abuts a portion of the circumference of the pin groove bottom-wall on the left side. This left hand portion 40-increases to a width which is greater than the radial distance between the bottom wall of the groove 26 andthe bottom wall of the groove 30. Thus the lock tab 34' is insertable from the left and prevented from withdrawal from the right. The radial outer marginal portion 44 ofthe Iock tab is disposed in the rotor groove 26 while the radially inward marginal portion 46 is disposed vin the pin groove 30. An outer circumferential edge 45 of the marginal portion 44 adjacent the left end is adapted to abut the bottom wall of the rotor groove 26 to prevent the lock tab from rotating clockwise out of the position shown in FIGURE 2.

The retainer element 36 is vbest understoodin reference to FIGURE 3. There are two retainer elements shown for purposes which will become evident later. The re tainer elements are substantially identical so that only one need be described. The following description is in connection with the retainer shown on the right. Corresponding parts of the retainer shown on the left are identified by the same numbers.

The retainer element 36 is insertable between the pin groove 30 and the rotor groove 26 from the right since the arcuate left hand portion 48 has a maximum thickness or width no greater than the radial distance between the bottom walls of these grooves. One the other hand, the right hand portion 50` wraps around the circumference of the bottom wall of the pin groove 30 and increases in thickness so that the retainer element 36 may not be withdrawn circumferentially from the left. The retainer element 36 overlies the lock tab 34 with its radially outer marginal portion 52 lying in the rotor groove 26 and its radially inward marginal portion 54 lying in the pin groove 30. An outer circumferential edge 51 of the radially outer marginal portion 52 adjacent the right end of the retainer element 36 is adapted to abut the bottom wall of the rotor groove to prevent the retainer element from rotating counterclockwise out of the position shown in FIGURE 3. The inner circumferential edge of the retainer element 36 adjacent the right end includes a locking surface '56 which is skewed with respect to the iradius of the rotor 14 which passes through the centerv of the pin 26. Thev function of the locking edge will be understood in the `below described assembly of the Iblade pin retainer. The right hand ends of the retainer elements 36 may include additional material such as that shown by the portion 58 in the retainer shown at the left. By adding various amounts of material to one or more of the retainers as shown in the left, it is possible to balance the rotor should it be required.

The pin blade retainer is assembled in the following manner. The lock tab 34 is first inserted into the aligned grooves 26 and 30 circumferentially from the left until its inner circumferential ends abut the bottom wall of the pin groove 30. It is then rotated slightly clockwise until edge 45 abuts the bottom wall of the rotor groove 26. The retainer element 36 is then inserted circumferentially from the right so that it overlies the lock tab 34 and until its inner circumferential edge also abuts the bottom wall of the pin groove 30. It is then rotated counterclockwise 3 until edge 51 abuts the bottom wall of the rotor groove 26 With both the lock tab 34 and the retainer element 36 in the position shown in FIGURE 3 the bendable portion 42 on the lock tab 34 is then bent up into the phantom line position where it engages the ylock edge 56 on the right hand portion of the retainer element 36. In the assembled position, the -bent up end 42 prevents withdrawal of the retainer element 36 circumferentially from the right while its enlarged `right hand portion 50 prevents withdrawal circumferentially from the left. Abutment edge 51 on the radially outer marginal portion 52 is adapted to abutment of the bottom wall of the rotor groove 26 so as to limit rotation -of the retainer element 36 about the pin groove 30 in the counterclockwise direction. The end 42 being bent up to abut locking surface 56 prevents clockwise rotation.

In like manner, the abutment of the bent portion 42 on the lock tab 34 with the locking edge 56 on the retainer element 36 prevents circumferential withdrawal of the lock tab 34 from the left `and counterclickwise rotation of the lock tab. The enlarged left hand portion 40 on the other hand prevents circumferential -withdrawal from the right while the abutment edge 45 on the radial outer margin of the lock tab 34 engages the bottom wall of the rotor groove 26 to limit rotation of the lock tab 34 about the pin 26 in the clockwise direction. The lock tabs 34 and retainer elements 36 thus joined from a blade pin retainer which secures the pin 26 in the aligned apertures 20 and 22 of the rotor and blade roots, respectively. FIGURE 4 shows the blade pin retainer in its final assembled position. It is to be understood that both abutment surfaces do not necessarily have to actually abut the bottom wall of the rotor groove as the retainer may accommodate a slight rotational play.

For disassembly, each `blade may be individually removed from the rotor 12 by merely bending down the end 14 of its lock tab 34, rotating the vretainer element 36 slightly, and withdrawing it circumferentially from the right. The lock tab 34 is then rotated counterclock-wise slightly and withdrawn from the left. The pin may then be removed and blade 18 demounted from the rotor 12. Preferably, a new lock tab will `be used in reassembling the blade to the rotor.

Thus it can Abe seen that I have provided a blade pin retainer which provides two-way retention for the pin 24. The retainer is designed so that each blade 18 may be individually mounted or demounted on the rotor 12. The rotor 12 requires no mounting apertures or other weakening types of modification and the blade pin retainer is of relatively cheap manufacture and structural simplicity. Additional material may be added to the blade pin retainer to balance the rotor. Thus I have incorpo-rated all of the features in my 4blade retainer as set forth above.

Various modifications are contemplated and may obviously be resorted to by those skilled in the art without departing from the spirit and scope of the invention as hereinafter defined by the appended claims, as only a preferred embodiment thereof has been disclosed.

I claim:

1. A blade -pin retainer for a bladed rotor in which the blade roots are mounted on the rotor by axial pins disposed in aligned apertures in the blade roots and rrotor and in which the rotor has a flange extending axially from a face thereof provided with a groove opening toward a groove adjacent an axial end of each of said pins, said pin grooves 'being aligned with said rotor groove, comprising, in combination, a lock tab for each of said pins having one end portion -circumferentially insertable between said aligned grooves with a bendable portion on the end thereof, a retainer element for each of said pins overlying each of said lock tabs and having one end portion circumferentially insertable between said aligned grooves and a ilocking edge adjacent the Opposite end thereof, said locking tabs and retainer elements being inserted from opposite sides of said pins and said bendable portions on said lock tabs being bentover said lock edges, whereby said lock tabs and said retainer elements are held in their operative positions to form said blade pin retainers, said blade pin retainers having a portion disposed in said rotor groove, and a portion disposed in said pin grooves whereby said pins are retained in said aligned apertures to mount said blades 0n said rotor.

2. The blade pin retainer as defined in claim 1 ywherein the insertable end portions of said lock tabs and said retainer elements have a width no greater than the radial distance between the bottom walls of said rotor groove and said pin grooves and wherein portions adjacent the opposite ends of said lock tabs and said retainer elements have a width greater than said radial distance.

3. The blade pin as defined in claim 2 wherein each of said lock tabs has a radially outer marginal portion disposed in said rotor groove and a radially inner marginal portion disposed in said pin grooves and wherein each of said retainer elements has a radially outer marginal portion disposed in said rotor groove and a radially inner marginal portion disposed in said pin grooves.

4. The blade retainer as defined in claim 3 wherein said radially outer marginal portions on said lock tabs have an abutment edge adjacent their said opposite ends adapted to abut the bottom wall of said rotor groove to .prevent rotation `of said lock tabs about said pins in one direction and -wherein said radially outer marginal portions on said retainer elements have an abutment edge adjacent their opposite ends adapted to abut the bottom wall of said rotor groove to prevent rotation of said retainer elements about said pins in an opposite direction, said bent up lock tab cooperating with said locking edge to prevent rotation of said lock tabs in said opposite direction and said retainer elements in said one direction.

5. The blade retainer as defined in claim 4 wherein said rotor flange is adjacent the outer circumferential edge thereof With said rotor groove opening radially inwardly.

6. The Iblade retainer as defined in claim 5 wherein each of said retainer elements has its opposite end selectively weighted to balance said rotor.

7. The blade retainer as defined in claim 1 wherein each of said retainer elements has its opposite end selectively weighted to 'balance said rotor.

No references cited.

MARTIN P. SCHWADRON, Primary Examiner.

E. A. POW/ELL, IR., Assistant Examiner. 

1. A BLADE PIN RETAINER FOR A BLADED ROTOR IN WHICH THE BLADE ROOTS ARE MOUNTED ON THE ROTOR BY AXIAL PINS DISPOSED IN ALIGNED APERTURES IN THE BLADE ROOTS AND ROTOR AND IN WHICH THE ROTOR HAS A FLANGE EXTENDING AXIALLY FROM A FACE THEREOF PROVIDED WITH A GROOVE OPENING TOWARD A GROOVE ADJACENT AN AXIAL END OF EACH OF SAID PINS, SAID PIN GROOVES BEING ALIGNED WITH SAID ROTOR GROOVE, COMPRISING, IN COMBINATION, A LOCK TAB FOR EACH OF SAID PINS HAVING ONE END PORTION CIRCUMFERENTIALLY INSERTABLE BETWEEN SAID ALIGNED GROOVES WITH A BENDABLE PORTION ON THE END THEREOF, A RETAINER ELEMENT FOR EACH OF SAID PINS OVERLYING EACH OF SAID LOCK TABS AND HAVING ONE END PORTION CIRCUMFERENTIALLY INSERTABLE BETWEEN SAID ALIGNED GROOVES AND A LOCKING EDGE ADJACENT THE OPPOSITE END THEREOF, SAID LOCKING TABS AND RETAINER ELEMENTS BEING INSERTED FROM OPPOSITE SIDES OF SAID PINS AND SAID BENDABLE PORTIONS ON SAID LOCK TABS BEING BENT OVER SAID LOCK EDGES, WHEREBY SAID LOCK TABS AND SAID RETAINER ELEMENTS ARE HELD IN THEIR OPERATIVE POSITIONS TO FORM SAID BLADE PIN RETAINERS, SAID BLADE PIN RETAINERS HAVING A PORTION DISPOSED IN SAID ROTOR GROOVE, AND A PORTION DISPOSED IN SAID PIN GROOVES WHEREBY SAID PINS ARE RETAINED IN SAID ALIGNED APERTURES TO MOUNT SAID BLADES ON SAID ROTOR. 